Concrete is typically poured into forms which permit the concrete to set in a desired shape or configuration. The forms are then removed, leaving the solidified concrete to form a structural member, such as a wall or the like. In small construction jobs, plywood may be used as the form and supported by wood studs until the concrete hardens into the desired shape. Such forming practices are well known but not particularly economical when a builder must repeatedly form similar walls during a series of construction projects.
For this reason, reusable concrete forming panels of metal have been developed which may be positioned and held together to provide a concrete forming wall with a central cavity. Such known forming panels include those shown in, for example, U.S. Pat. Nos. 4,708,315, 4,958,800, 5,058,855, 5,184,439, and 5,965,053, the disclosures of which are incorporated herein by reference. Aluminum forming panel systems provide faster construction set up than standard steel and plywood systems, are lighter in weight, and typically leave a smooth wall surface which is better looking than other construction form systems.
Aluminum forming panel systems typically employ pin and wedge systems that are simple to use and easy to handle, and tie bars which connect opposed wall forming panels to receive concrete therebetween. In addition, steel plates may be riveted to the sides of the forming panels to provide bushings for receipt of hardened objects such as pins therethrough. Because of the wear of steel pins and wedges against aluminum surfaces and the use of tie bars to connect opposed panels, the steel bushings have been required to provide the existing aluminum forming panels with a satisfactory useful life.
While rugged aluminum concrete forming panels have been successful in use, they nonetheless require substantial material in order to withstand the loads and wear imposed by use at a construction site. This, and the use of steel plates as bushings increases the overall weight of the forms which may be significant to the user when multiple forms are in use. There has thus developed a need for a forming panel useful in many environments which includes less steel and is lighter in weight than past aluminum forming panels.
These objects have largely been met by the concrete forming panel with lightweight sidewall in accordance with the present invention. That is to say, the concrete forming panel hereof is strong, rugged, and able to withstand wear imposed by the contact of the frame with steel pins and wedges by a wear element of a material having a greater hardness than the bushing on which it is received, thereby permitting overall reduction in weight and providing selective reinforcement of wear-prone areas of the bushing and frame.
In greater detail, the invention hereof includes a face sheet secured, preferably by welding, to a surrounding frame having at least one side rail and preferably opposed end rails and side rails. The side rail may be provided as a relatively thin member such as a sheet of formed or extruded aluminum. Lightweight reinforcement bushings, typically of aluminum, are either spaced or provided continuously along the side rails or end rails. The aluminum reinforcement bushings include a hardened wear element, such as steel reinforcing rods extending longitudinally along the rails which are preferably attached to the bushing leaving a portion of the wear element exposed. The wear element is preferably positioned adjacent an opening through the aluminum reinforcement bushing, the opening being in registry with a hole in the rail in order to provide wear surfaces. Pins placed through these holes thus bear, at least partially, against the steel wear elements to inhibit expansion of the opening. Further, the steel wear elements, such as steel washers or reinforcing rods, are preferably embedded in the aluminum reinforcement bushings in a manner to present an exposed portion against which the head of a connecting pin or its securing wedge may bear when the form is in use. The reinforcing rod maybe provided as a single longitudinally extending rod, or more preferably two parallel longitudinally extending rods positioned diametrically opposite the hole in the aluminum bushing, either on the same face of the bushing or on opposite faces. The wear elements also have a higher modulus of elasticity than the aluminum rails and bushings, and thus provide increased strength for the frame.
The end rail and side rail may be cast, forged or machined of material, typically aluminum, and is significantly thinner in cross section than that previously employed in concrete forming panels, or may be extruded having hollow chambers to reduce the amount of material in any cross-sectional area relative to prior aluminum forming panel frames. The side rail preferably has a face sheet edge welded to the face sheet of the forming panel and an exposed edge provided with a rounded shoulder. Preferably, the side rail is provided with a thinned central waist with thicker portions adjacent the edges, as by concentrating the added material along the edges produces a more efficient means of addressing stress concentrations in the forming panel.
As a result of the present invention, a lightweight forming panel may be provided which nonetheless is rugged and maintains its shape in use. The steel reinforcing rods are positioned in critical locations to reduce the amount of material required in constructing the forming panel and reduce wear during use. The positioning of the steel reinforcing rods adjacent the holes in the side rail inhibit expansion of the hole due to the hardness of the steel pins and wedges wearing against the aluminum and the resulting misalignment of adjacent panels which yields uneven poured concrete surfaces. Additionally, the steel reinforcing rods resist cocking of the pins relative to the desired insertion/extraction axis, which makes the steel pins dig into the aluminum surfaces and increases the difficulty of removal. The steel reinforcing rods give a hardened surface for the wedge to bear against, and add strength to resist deformation of the frame by impact or other loads applied thereto.
Because of the thinning of the side rail itself, the face sheet has a smaller distance from its edge to the weld, resulting in a smaller cantilever arm from the weld to the edge of the face sheet. This helps in resisting “peeling” of the face sheet from the side rail or end rail. The aluminum bushing is preferably shaped to provide a cove especially configured to provide for this first weld bead between the side rail and the face sheet on the inside corner formed therebetween, and thereby facilitate this reduction of the moment arm.
These and other objects of the present invention will be readily apparent to those skilled in the art with reference to the description and drawings which follow.